Persons with serious mental illness (SMI), such as schizophrenia and bipolar disorder, die on average 25 years earlier than persons without SMI. Much premature death in SMI is attributable to CVD with CVD-related mortality rates twice those of the overall population. Accordingly, this vulnerable group, comprising at least 15 million Americans, has a high burden of modifiable CVD risk factors including smoking, obesity, hypertension, diabetes, and dyslipidemia. The American Heart Association (AHA) recently set ambitious strategic Impact Goals to improve the cardiovascular health of all Americans and reduce deaths from CVD by 20 percent by 2020. Substantial efforts are underway to meet these goals in the general population. Still, interventions need to be adapted for persons with SMI who often have substantial barriers related to cognitive impairment and psychiatric symptoms. Hence, without special efforts to promote CV health and control risk factors in vulnerable populations like the SMI, it is unlikely that CV health will improve in SMI patients, and disparitis in CV health will not only persist, but likely worsen. In view of their extraordinary burden of CVD risk factors, the overarching objective of this R-01 application is to develop and test a scalable intervention that could be widely adopted to reduce risk in this vulnerable population. Our multidisciplinary research team has expertise designing and rigorously testing interventions to decrease CVD risk in the general population and in persons with SMI. We propose the IDEAL Trial, a community organization-based, two-arm clinical trial that will test the hypothesis that an 18-month comprehensive, practical CVD risk reduction program will be superior to control in improving CV health in persons with SMI. We will partner with a large mental health care organization and enroll 250 persons with SMI who attend 4 psychiatric rehabilitation day programs or adjoining mental health clinics. Rehabilitation programs provide opportune settings to implement CVD risk reduction programs because patients attend several days a week and environmental components can take place on-site. We will provide a common background of exercise classes and healthy changes to meals served. Participants will then be randomized to receive this control condition or the 18-month active IDEAL intervention with a Heart Health Interventionist, who will provide on-site: 1) individual CVD risk reduction behavioral counseling (e.g., for smoking cessation, diet); 2) coordination with primary care providers to ensure appropriate management of risk factors (e.g., blood pressure control); and 3) collaboration with mental health staff and social supports to encourage and motivate participants to reach goals. The primary outcome will be the change in estimated CVD risk from the global Framingham Risk Score; secondary outcomes will include AHA metrics for CV health. Accomplishing meaningful reductions in CVD throughout the population will require targeted interventions focusing on vulnerable, high-risk groups such as those with SMI. If successful, this trial will provide persuasive evidence for use of a practical, comprehensive CVD risk reduction strategy in SMI to reduce health disparities.